Cross roller bit



Jan. '11, 1938. SCOTT ET AL 2,104,821

CROSS ROLLER BIT Filed Jan. 25, 1936 NEEZPZETH fl/YD [1.56077] INVENTORS Haj v NJ/Mich ATTORNEY Patented Jan. 11, 1938 UNITED STATES PATENT OFFICE Application January 25, 1936, Serial No. 60,793

'l'Clnims.

Our invention relates to roller boring drills for use in drilling deep wells for oil, gas, sulphur and the like. It has particular reference to the means for mounting the cutters in the forward end of the head.

It is an object of the inventionto provide a carrier assembly upon which the rotating cutters may be mounted and quickly and conveniently assembled in the head of the drill.

We desire to provide an assembly which can be cheaply and easily fitted into a recess in the forward end of the head and secured in position by welding.

It is an object of the invention to provide a mounting for the cutters which is shaped to fit the recess in the head and to be welded thereto. Because of our method of attachment the head need not be carefully machined or prepared to receive the assembly but the mounting for the cutters may be fitted in place and quickly and accurately secured in position in a simple and economical manner.

Another object includes means to prevent distortion of the bit head in welding the cutter assembly in place.

Referring to the drawing herewith, Fig. 1 is a central vertical section through a drill bit embodying the invention.

- Fig. 2 is a similar vertical section taken at 1 approximately right angles to that shown in Fig. 1.

Fig. 3 is a bottom plan view of the drill.

Fig. 4 is a vertical section through the lower end of a drill employing a slightly difl'erent embodiment of the invention. 7

The type of drill to which our invention is applied is an ordinary one and commonly designated as a cross roller bit. It has a head I having an upper tapered shank 2 threaded for engagement with a drill collar.

The lower end of the bit has two pairs of opposed forwardly extending legs, one pair, shown at 3, 3, in Fig. 1, have inner faces formed with an upwardly and inwardly inclined wall 4 thereon. The other pair of legs, shown at 5, are arranged between the pair of legs 3 and extend vertically downward. Between the two pairs of legs is thus formed a recess or chamber 6 within which the cutter assembly is mounted.

The cutter assembly includes a transversely extending bridge I projecting across the recess at the forward end and between the two inclined faces 4, 4. Between its ends it is flattened as shown at B in Fig. 2. The portions of the bridge toward the ends are upwardly and outwardly inclined and formed cylindrically to furnish a support 9 for the side cutters Ill. The extreme end surfaces of the bridge are flattened off to come approximately flush with the inner faces 6 4 of the cutter recess.

The cutters ID are mounted upon the shafts 9 of the bridge and are adapted to roll upon antifriction bearings il formed upon the said shaft portions 9. On their outer ends adjacent the 10 flattened face 4 of the recess are thrust washers l2, which are held stationary in that position and form a wear surface at the outer ends of the side cutters. The roller bearings I l abut at their outer ends against the washers l2 and at their inner ends against a shoulder I3 formed on the bridge, as will be understood from Fig. 1.

The legs 5 support the cross roller shaft l4, which is shown in the drawing as extending across the cutter recess and through an opening in the bridge 1. The ends of the cross roller shaft come approximately flush with the inner faces of the downwardly extending legs 5 and the openings formed in the legs at this point.

Cutters I5 and I6 mounted upon the cross roller shaft cut the central portion of the hole. As

-will be seen from Fig. 2 the bridge 1 is ofl'set slightly from the center of the shaft l4 and that cutters l5 and it are not of the same length, one being longer than the other to extend past 80 the center of the hole. The cross roller cutters are mounted upon anti-friction bearings i1 and the ends of the cutters are separated from the legs 5 by thrust washers l2.

The bridge and cross roller shaft with the cutters thereon may be assembled in the position shown in the drawings and inserted upwardly in assembled condition into the cutter recess. The assembly may then be secured in position 40 by welding the ends of the shafts to the side walls of the recess. In order to do this openings are formed through the legs 3 and 5 to receive bonds of welding metal to engage the ends of the shaft'and bridge. Bonds of welding metal I8 secure the bridge to the legs 3. The openings are larger than the ends of the said shaft and bridge so that the bonds of welding material also engage the washers I2 at the ends of the cutters l0 and secure them also rigidly in place as an integral part of the bridge.

At the ends of the cross roller shaft l4 bonds of welding material l9 secure the ends of the shaft I4 and the washers l2 integrally to the legs 5. This welded connection may be easily and quickly formed and as will be obvious the machining of the ends of the shaft or bridge need not be accurately done and all that is necessary in preparing the carriers for the cutters is to properly machine the bearings upon which the cutters rotate. The assembly is practically self centering and the operation becomes an economical-one.

This form of construction may be cheaply made and when the supporting carrier has been mounted in the head as described a strong and integral construction of bridge, shaft and head is secured which avoids any possibility of loosening of the bridge or shaft from the head in use.

In forming welds at both ends of the shaft it is found that the result of the expansion and contraction of the metal due to the welding tends to draw the legs of the bit in towards the ends of the shaft with. a powerful force tending to clamp the legs against the bearings. In the Fig. 1 form this action is taken up by the shoulders and washers H2 at the ends of the bridge member. In the Fig. 4 embodiment, bushings 20 are placed upon the shaft i4 between the shoulders 2E upon the shaft and the washers i2 at the ends of the cross roller shaft. The rollers then roll in raceways in the bushings. The bushings space the legs 5 and prevent the clamping action. due to welding from acting to crowd the cutters and prevent rotation. We are, therefore, assured of a free rolling of the cutters in operation.

So far as our patent application goes there are only two parts to the bit: (1) The cutter assembly, and (2) the bit head. The cutter assembly is accurately made so that it its gage diameter is determined by the bearings and shafts on which the cutters are mounted. The gage of hole cut with this cutter assembly has no relation whatever to the accuracy of the head to which the cutter assembly is secured. The only functions of the bit head are: (1) To force the cutters to turn on bottom of the hole; (2) provide jets for cleaning the cutters; and (3) lift the worn cutters out of the hole.

We have designed a cutter assembly which may be dropped into the open end of a forked head, and be welded through holes provided in the ends of the forks to secure the cutter assembly to the head. i

Since the head is merely a holder for the cutters and since the cutter assembly has been made accurately as a unit in itself, no machining is necessary on the head where the cutter assembly rests.

Since the cutter assembly has no projecting lugs as in other designs, considerable expensive jigging and machine work is eliminated. Only a drill press is necessary to drill holes in the head. approximately opposite the ends of the cutter shafts. The novelty of this device resides in the fact that there are no projecting lugs from the cutter assembly, thus eliminating expensive 7 machine work and high investment costs to provide accurate seats for the shafts.

head forming a cutter receiving recess betweenv them, the inner faces of one pair of legs being inclined upwardly and inwardly, a bridge, upwardly and outwardly inclined cutter supports thereon, the end surfaces thereof flattened to come approximately flush with said inclined faces, side cutters rotatable on said supports adjacent said" ly and outwardly inclined cutter supports thereon arranged at substantially right angles to said inclined faces, the ends of said bridge being approximately flush with said faces, side cutters rotatable on said bridge adjacent said faces, a cross roller shaft extending through said bridge and having its ends approximately flush with the inner sides of the other pair of said legs, cutters on said cross roller shaft, and means engaging the ends of said shaft and bridge to secure the same integrally to said legs.

3. A roller well drill including a head, two opposed pairs of forwardly extending legs on said head forming a cutter receiving recess between them, the inner faces of one pair of legs being inclined upwardly and inwardly, a bridge, cutter bearings on its ends inclined upwardly and flattened to lie approximately flush with said inclined faces, side cutters rotatable on said bridge adjacent said faces, a cross roller shaft extending through said bridge and having its ends adjacent the inner sides of the other pair of said legs, cutters on said cross roller shaft, bonds of welding metal securing said bridge and shaft rigidly said inclined faces, side cutters rotatable on said bridge adjacent said face, a cross roller shaft extending through said bridge and having its ends adjoining the inner sides of the other pair of said legs, cutters on said cross roller shaft, washers on said bridge and shaft between said cutters and said legs and means securing said washers and said bridge and shaft integrally to said legs.

5. A roller well drill including a head, two pairs of 'opposed legs extending forwardly from said head, a bridge having its ends approximately flush with the inner faces of one of said pairs of legs, a cross roller shaft'extending through said bridge and having ends approximately flush with the inner faces of the second pair of legs, cutters on said bridge, cutters on said shaft, washers on said ends separating said cutters from said legs, and bonds of welding material securing said ends and said washers integrally to said legs.

6. A roller well drill including a head, a cutterreceiving recess in the forward end thereof, a bridge, a shaft transversely of said bridge, cutters on said shaft and bridge, said shaft and bridge having ends fitting in said recess adjacent the inner walls thereof, and bonds of welding material uniting said ends and said walls.

7. A roller well drill including a head, a cutterreceiving recess in the forward end thereof, a

bridge, a shaft transversely of said bridge, cutwalls to space said shoulders from said walls, and ters on said shaft and bridge, said shaft and bonds of welding material uniting said ends and bridge having ends fitting in said recess flush with said walls.

the inner walls thereof, outwardly presented FLOYD L.SCO'1'1.'

5 shoulders on said bridge and shaft, means on the NELSON B. BERLETH. 5

ends of said bridge and shaft adjacent said recess 

